1. Field of the Invention
This invention relates to a hydrocarbon composition capable of being suitably used as a refrigerant for use in air conditioners and refrigerators or a detergent for cleansing precision components such as semiconductor chips and mother boards in computers and parts in hard disk drives or other precision instruments.
2. Description of the Related Art
The so-called chlorofluorocarbons (CFC) such as dichlorodifluoromethane and monochlorodifluoromethane were in heavy usage as a refrigerant for use in air conditioners and refrigerators or a detergent for cleansing or washing precision components. It has been pointed out that CFCs have the advantage of safe incombustibility, high stability, and lower toxicity, whereas CFC destroys the ozone layer, consequently to exert a serious influence upon the global environment. Thus, the production and use of CFC have been gradually reduced and now tend to be abolished totally.
Accordingly, there have been developed a variety of alternatives for chlorofluorocarbon. As typical of the alternatives for chlorofluorocarbon, the so-called HFC such as 1,1,1,2-tetrafluoroethane and 1,1,1-trifloroethane has been known. HFC does not degrade the ozone layer so much, but it has an adverse environmental effect to cause global warming, thus leaving room for improvement in HFC.
Under the circumstances, intense interest has lately been shown toward hydrocarbon compositions as one of alternatives for chlorofluorocarbon (hydrochlorofluorocarbons). The hydrocarbon compositions advantageously have low ability to destroy ozone and cause global warming.
For instance, Japanese Patent Application Public Disclosure No. HEI 01-139676(A) discloses working medium composites containing, as essential components, at least one selected from the group consisting of hydrocarbons having a carbon number of 4-5, monochlorodifluoromethane and monochloropentafluoroethane. As the hydrocarbons having a carbon number of 4-5, there are disclosed n-butane, isobutane, cyclobutane, n-pentane, isopentane, and cyclopentane. Other hydrocarbon compositions are disclosed in Japanese Patent Application Public Disclosures Nos. SHO 54-6881(A), SHO 54-6882(A), and HEI 01-139677(A).
Japanese Patent Application Public Disclosure No. HEI 08-176536(A) discloses a refrigerant consisting of a saturated hydrocarbon containing an unsaturated hydrocarbon. This further discloses a preferable refrigerant made by mixing a first refrigerant component consisting of a saturated hydrocarbon containing an unsaturated hydrocarbon, a second refrigerant component consisting of at least one of a hydrogenated fluorocarbon refrigerant and a carbon fluoride refrigerant, which have higher boiling points than that of the first refrigerant component, and a third refrigerant consisting of a saturated hydrocarbon having a higher boiling point than that of the second refrigerant component. In this conventional art, propane and butane may be used as the aforementioned saturated hydrocarbon by way of example.
Also, U.S. Pat. No. 6,336,333 discloses a refrigerant mixture of propane and butane.
The conventional hydrocarbon compositions described above are generally used in the state combined with CFC, HFC or the like and therefore, these are undesirable from the standpoint of the protection of the environment. Thus, a need has been felt for hydrocarbon compositions capable of being independently used as a refrigerant.
To be more specific, the aforementioned refrigerant consisting of propane and butane has the following problem. That is, the refrigerant consisting of propane and butane is apt to be decomposed to these components when leaking outside a cooling system or other apparatuses. As a result, the refrigerant left in the cooling system possibly breaks down the balance of its essential compositions, and consequently, it needs to be replaced entirely with a new refrigerant when being renewed, resultingly to shorten the life of the system.
Moreover, the aforementioned refrigerant consisting of propane and butane has a low ignition temperature in the order of 400° C. due to weak intermolecular binding power of the components thereof and has a problem from the viewpoint of safety. Thus, there has been a great need for a safe, superior hydrocarbon composition having higher ignition temperature.